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Listening test vs. tech data

Having heard the "work in progress" today, I would say they sounded wonderful.
Lots of high frequency "sparkle" and the famous JBL dynamics. I sincerly doubt the addition of any tweeter, super or otherwise, would add to the enjoyment of the upper end. Thanks Zilch. I'd love an invite when YOU think the design is finished.

FYI, if you export an ASCII file from the WT2 and have a look you will find that the terminal impedance (the actual crossover load) has been split into real (resistive) and imaginary (inductive) components. Using this in your circuit simulator should give you results that are very accurate.

The next WT2 software release will of course have the same stuff as the original, but also include some frequency dependent R's and L's to better match the Z curve.

Note: The 'results' pulldown has a sub menu for copying Q/Fs, Vas or Box sweeps to an arbitrary buffer. After copying to the arbitrary buffer, you can then view that data in the arbitrary format inside the results window, and that includes the R/I split out.

I was expecting the entire knee to shift leftward, but constant Q seems to be the right approach, as the response is nowhere near flat in that region. Part of what it's doing is attenuating a 5 dB peak there. Am I starting to get this?

What tool(s) do I need to get on the same page and raise my level of incompetency here?

Secured in a late-night run to Sunnyvale yesterday, second Citation 7.4 purchased for me by JuniorJBL (he wanted the driver, I wanted the box,) was picked up and delivered upstate by Ti Dome. Many thanks to these generous forum members!

Here, they're loaded with new butyl-surround LE14H-3 for testing in combination with 2431H and PT-F waveguides. So far, so good. We're breakin' 'em in today.

Johnaec's comin' over later to listen to the several iterations of "Q&D" here. L200 cab version visible behind these....

These two Citations, both made in 1995 from the date codes on the stealth filters in them (see above), have different depths. The newer one (left) is 1.25" deeper (16.75" vs 15.5"), and made from thicker material, apparently (1" vs. 3/4"?), with less internal bracing. Didn't notice until AFTER I'd loaded them woofers, of course.

Port on older one (right) is unflared, as described earlier by Giskard. Straight pipe, 4" dia., 8" deep.

Design subject to change without notice, apparently. Guessin' it was cheaper to make them thicker than to keep strugglin' with compound cross-bracing inside.

OK - I was able to make it over to Zilch's today to pick up some speakers he'd picked up that Titanium Dome had graciously brought up from Anaheim for me, (thanks, Dome!).

I was finally able to listen to a couple iterations of the various designs Zilch has been working on. These were also compared with Zilch's stock 4430's, though those were in a different listening room. We used the same source material for all tests so relative comparisons were easier.

The sets made up of the LE14H-3's, 2431H's and PT-F waveguides were pretty surprising. Both the LF and HF were better than I would have expected, especially with such a flat little horn. I understand the LF was just using natural roll-off at the high end, while the crossover design for the HF duplicates JBL's design from their pro-series speakers using this HF combination. This resulted in exceptionally flat response all the way out to 20K, as noted in an earlier message. This HF combination was also used in Zilch's L200's. In both these cases, there was noticeably extended HF response compared to the two systems we listened to with the 2344 horns. Dispersion does narrow noticeably in the last half-octave with the PT-F horns, but the extended response is definitely there. The L200 version did exhibit deeper bass with the 2235's than the LE14H-3, but much of this was likely because they were sitting on the floor, and much closer to the wall. The LE14H-3 did seem to feel "tighter" in the low end, though - I actually preferred these over the 2235's.

As mentioned, we also listened to the "quick and dirty" set, made up of B380 cabinets with the 2344's sitting on top, and also Zilch's stock 4430's . As expected, these pretty much matched the sound of each other, with the exception that the stock versions produced noticeably stronger bass, but again, this was likely because the stock ones were on the floor and against a wall.

Dispersion of both HF systems, (2344 and PT-F), was very good, although the 2344's seemed to be a little more "spacious" than the PT-F, though the extended HF response of the 2431H's with the PT-F was better. What I think is happening here is that the PT-F's seem more "point-source" because the driver throat is completely open in the PT-F, which means you're getting a direct shot at the source, unlike the 2344, which squeezes down before the flare. This makes the sound from the PT-F's easier to pinpoint, as compared to a more nebulous source with the 2344's, though the difference is relatively minor. It's the extended HF response of the 2431H which is most noticeable.

The big thing I took from all of this is how closely the general sound of all four systems sounded, the logical conclusion given the similar RTA response. When running with such flat curves, many would tend to consider this a somewhat "dry" sound, but being flat is definitely a better place to start from compared to many high-end speakers that get rave reviews for what I consider "colored" sound, usually in a form of loudness compensation being built into the response. While the average user may prefer this "colored" sound, it's far better to start with flat response and tailor the sound yourself, rather than having the speaker sound "tailored" by the manufacturer. The flat frequency response of JBL's is one of the main reasons for their stature - you're getting accurate reproduction to start with instead of "colored" or "tailored" sound. Zilch's versions prove this isn't a fluke!

I also got to see the mock-up of Zilch's "trapezoid" design. It really looks much better in person than the pics, at least as far as volume/mass goes. I think these finished in nice veneer will be quite attractive! And the combination of LE14's and the 2431H/PT-F is a very attractive proposition! Simple, inexpensive 2-ways with exceptionally flat response, and without all the complexity of getting 3 or 4 way components all operating together.

Anyway, it was a lot of fun. We're lucky to have someone like Zilch here, to actually produce the crossover/driver variations to really conclusively nail down how all the combinations sound and compare. And someone looking to put together a straightforward, good sounding 2-way system should really take advantage of the groundwork Zilch has laid down!

Thanks, Zilch!

PS - 'also wanted to mention how great the L200 foam grilles from Sonofagun looked - another great resource!

I was expecting the entire knee to shift leftward, but constant Q seems to be the right approach, as the response is nowhere near flat in that region. Part of what it's doing is attenuating a 5 dB peak there. Am I starting to get this?

What tool(s) do I need to get on the same page and raise my level of incompetency here?

Zilch, how do you damp the 2431H? L-Pad? And if so where did you install it "in" the AM Network topology?

That's an issue I haven't addressed yet. I've always run these systems biamped, so I don't know what padding will be required to run HF and LF together. That's another reason we need to get you up and running, so we can compare notes on the optimum approach.

Simplest would be an L-Pad just before the HF driver, assuming it's the HF that needs padding; the impedance varies between about 6.5 and 9 Ohms in the operating range, so any padding will alter the crossover curve. I'll generate new impedance curves on all of the 2431H's here as part of that effort.

As you know, the original padding was done with the crossover component selection itself. How that balances with 2235H and LE14A and H, I haven't yet determined.

Originally Posted by Guido

Another Point: Did you ever try the 2431H on the 2344 Horn. Maybe with reversing the Adaptor you sent me? Could be a nice combo. What do you think?

Nope, never tried that. Once I found a viable alternative to NLA 2344(A), I ran with that. Sounds like something you might try, tho, since you have all of the parts (soon).

PT-F is physically easier to integrate into various system designs. While 2344A will "fit" into L200, for example, and even be concealed by the grille, the deep overhang at the top could easily create reflections. Also, it's obvious that my own Z1 cabinet design would have to be 6" taller to accommodate PT-H or 2344A. Thus, I abandoned the larger square horns in favor of the compact format early on.

While the pattern control of the compact PT-F is not as precise, perhaps, the white paper states that its distortion is lower. They measure and sound the same to me, but Johnaec hears a difference in directivity in the last half-octave. We'll likely follow up with polar response tests on these....

Originally Posted by Guido

Zilch, I didn't get this. Maybe the language barrier

How exactly can I assist you here?

Mr. Widget has CLIO FR curves on the three different crossover component combinations we have tried, which he'll likely post here soon. You'll see the results of the tweaks we've tried so far at higher resolution than I can achieve with simple 1/3 octave RTA.

Given that we have FR and impedance curves for the drivers on PT waveguides, my question is, "What software tools do I need to design and sim the crossover we're using?"

You and Giskard seem to be using similar (if not the same) tools. What do I need to purchase to get onto the same page? Xover 3 Pro?